体循环, or "circulation," refers to the movement of blood throughout the body. This process is essential for delivering oxygen and nutrients to cells while removing waste products. The heart acts as a pump, circulating blood through a network of arteries and veins. In the human body, there are two main types of circulation: 体循环 (systemic circulation) and 肺循环 (pulmonary circulation). Systemic circulation carries oxygen-rich blood from the heart to the rest of the body, while pulmonary circulation transports oxygen-poor blood from the heart to the lungs for oxygenation. Together, these systems maintain overall health and function.